Scars

How scars form

Wound healing has three overlapping phases:

1. Inflammation (days 1 to 5): bleeding stops, white blood cells clean the wound.
2. Proliferation (days 4 to 21): new blood vessels and collagen fill the gap; the wound edges pull together.
3. Remodeling (3 weeks to 2 years): collagen is reorganized and strengthened. The scar gradually flattens, softens and fades.

Scar tissue is made of collagen laid down in a less organized pattern than normal skin. It lacks hair follicles and sweat glands and is about 70 to 80 percent as strong as uninjured skin.

Types of scars

Hypertrophic scars vs keloids

Hypertrophic scars usually appear within weeks, stay within the wound boundary and often improve on their own over 1 to 2 years. Keloids may appear months later, extend beyond the original wound, rarely regress, and frequently recur after removal. Both can itch and hurt.

Risk factors for problem scars

• deep wounds, burns and wounds that take longer than 2 to 3 weeks to heal
• wound infection or reopening
• tension across the wound (chest, shoulders, back, joints)
• darker skin and family history (keloids)
• age 10 to 30 (keloids)
• smoking and poor nutrition, which slow healing (wound healing problems)

Caring for a new wound to minimize scarring

• Keep the wound clean and covered with petroleum jelly and a dressing so it stays moist, which heals faster than letting it scab.
• Do not pick at scabs.
• Have deep or gaping cuts closed promptly, ideally within hours.
• Follow stitch removal instructions.
• Once closed, protect from sun with clothing or high-SPF sunscreen for at least a year, since UV darkens scars.
• Gently massage the healed scar with a moisturizer for a few minutes daily to soften it.

Treatments for scars

At home

• Silicone gel or sheets: the best-supported first-line treatment for preventing and flattening raised scars; use daily for at least 2 to 3 months, starting once the wound has closed.
• Pressure garments for large burn scars.
• Sun protection.
• Massage and moisturizers.

Many over-the-counter scar creams, such as onion extract or vitamin E, have limited evidence.

Medical and procedural

• Steroid injections into hypertrophic scars and keloids, every 4 to 6 weeks, to flatten and soften them.
• Laser therapy: pulsed dye lasers reduce redness; fractional lasers improve texture of acne and surgical scars.
• Microneedling, chemical peels and subcision for acne scars.
• Fillers to lift sunken scars.
• Cryotherapy for keloids.
• Surgical scar revision: cutting out the scar and closing it more neatly, Z-plasty to reorient or lengthen it, or skin grafts. Keloids have high recurrence after surgery alone, so surgery is combined with steroid injections or radiation.
• Contracture release with surgery and physical therapy for scars that restrict movement.

When a scar needs checking

Rarely, a long-standing scar, particularly from a burn, can develop a skin cancer (Marjolin ulcer). A scar that changes, breaks down into a non-healing sore, or develops a lump should be examined.

Frequently asked questions

How long does it take for a scar to fade?

Most scars are red or pink and slightly raised for the first few months, then gradually flatten, soften and fade over 12 to 18 months. They do not disappear completely, but often become much less noticeable.

What is the difference between a keloid and a hypertrophic scar?

A hypertrophic scar is raised but stays within the original wound and often improves over time. A keloid grows beyond the wound edges, may keep enlarging, rarely fades on its own and often recurs after removal. Keloids are more common in people with darker skin.

What is the best treatment for scars?

For raised scars, silicone gel or sheets are the best-supported first step, along with sun protection and massage. Steroid injections, lasers and surgery help stubborn scars. Acne scars respond to lasers, microneedling, subcision and fillers. A dermatologist can tailor treatment.

Can scars be removed completely?

No treatment removes a scar completely, because scar tissue replaces normal skin. Treatments can make scars flatter, softer, paler and less noticeable. Surgical revision replaces a wide or raised scar with a finer one in a better position.

Why do scars itch?

Scars itch because nerve endings are regenerating and the new collagen and inflammation stimulate itch signals, especially in raised or burn scars. Moisturizers, silicone, massage and, for persistent itch, steroid injections or creams can help.